Propeller jig



' Ami] 2, 1940. E. x. ENDERLEIN PROPELLER JIG Filed y 12, 1938 3 Sheets-Sheet 1 INVENTOR,

ORNEY N! mm mm NY Y April 2, 1940. E. x. ENDERLEIN PROPELLER JIG Filed May 12, 1 938 3 Sheets-Sheet 2 v INVENTO R f/fMfl/VUEL X. 505m. E/N,

ATTOR N EY Patented Apr. 2, 1940 UNlTED STATES PATENT omcs PROFELLEit HG Emmanuel X; Enderlein; Grenl'och, N; j.

' Application May 12, 9st. seriai no. 207,493 7 2 Clainia (.01. 144-4445) Propellers for flying machines must, inorder to work, possess a predetermined shape, contour or profile over their entire surface to give them the pitch or camber desired under varying conditions and for different requirements.

In certain cases full size propellers for standard flying machines are carved or shaped by hand and there is a great and growing interest among amateurs in making small scale model aeroplanes, and associations of such amateurs exist over the entire country. i I I Heretofo-re, such propellers have been shaped by hand from drawings or models, and due to the I extreme accuracy needed in the pitch or camber of the blades great effort and great personal skill have been necessary.

It is therefore the object of my invention to produce a jig by means of which a rough piece of wood can be rapidly. and accurately shaped into a propeller having a predetermined pitch or carnpropeller of a corresponding redetermined carnb'er; but is is to be understood that by'varying' the contour or proportions of the jig itself any ber of diiierently shaped propellers can be produced.

Fig. 1 represents a plan view of a propeller jig" embodying my invention.

Fig. 2 represents a view in side elevation shdw- 7 ing the various parts of the jig before they are assembled and showing the blank from which a propeller is to be formed.

Fig. 2a representsia bottom plan view" or the uppermost part of the jig as shownin Fig. 2.

Fig. 3 represents a plan view of the blank shown in Fig.2 as it is shaped prior to insertion in the jig for cutting the blades.

Fig. 4 represents a view similar to Fig. 3 showing the blank after it is carved in the jig, but before its ends are trimmed.

Fig. 5 represents an end elevation of Fig. 2 with the-bottom clamp broken ofi.

Fig. 6 represents an end elevation similar to Fig. 5 but showing the jig" assembled and the blank to be cut clamped in position.

Fig. 7 represents a section on line L4 of Fig; I with the blank to be carved in position. v

Fig. 8 represents a section on line 8-8 of l,

but with the blank to be carved clam ed in osttics.

- Fig. 9 represents end elevation of the pro:

peller as shown in Fig. 4. i I I N Fig. 10 represents a section on line Ill -Ill of Fig". 4.

Fig. 11 represents a section on line of Fig. 4.

Fig. 12 represents a section on line 12-12 of Fig.4.

Fig. 13' represents a sectional view on line l3l 3 of Fig. l showing the blank in position and after one face of it has been cut.

Fig. 14 is a view similar to Fig. 13 showing the blank positioned in the jig and reversed, ready for the cutting of the other face thereof, and with an adjustable brace positioned underneath the Surface that has been clit t0 slipport the wood while the other facethereof is being cut. 7

Fig. 15 is a view similar to Fig. .14 showing the propeller after both sides thereof have been cut.

Fig. 16 represents a composite view showing a preferred form of construction of the adjustable brace used under the propeller being cut in Figs. 14- and -15.

Fig. 1 represents a fragmentary plan view of the end portion of the jig shown in 1 with a different form of brace for the blank being Clit;

Fig". 18 represents a sectionon line" l a -1'3 of Fig. 17 showing the brace supporting the blank being cut in the same manner as illustrated in Fig.14. v

Fig. 19 represents a perspective view of the form of brace shown in Figs. 17' and 18.

Referring to the drawings in which like refer ence characters indicate like parts, and particularly to Figs. 1 and 2, r'ny'novel jig consists of an elongated channel which is preferably provided with a swivel clam'p 2015f any desired construction for securing the jig to a work bench or the like. best seen in 1 the channel is provided with the rectilinear portions 22' and 24 which merge inwardly with the curvilinear restricted portions 26' and. The straight portion 22 and curvilinear portion are bounded along the rear edge thereof ('as' viewed inFigS. 1 and 2) with the inclined but relatively high rear wall 30 and along their front edge with the inclined but relatively low rim" or front wall 32. The straight portion 24' and the curvilinear portion 28', on the contrary, are provided with a relatively MW and inclined fear W211i 34 and a re1ativeiy high inclinedfront wall 36'. Therear high- 38 to form a recess which accommodates the part of the jig best seen in Fig. 2a, and which consists of a member 39 provided with a hole 40 adapted to be engaged by the bolt 62 which is preferably the same bolt that secures the clamp 20 to the jig. 44 designates a nut for holding the member 39 in place. The top member 39 of the jig, as best shown in Fig. 2a, has an oblong, slanted, gently curved edge 43 and a relatively shorter, more inclined, and more sharply curved edge 59 with the opposite ends 52 thereof cut at an angle so as to abut against the angularlycut edges 38 of the walls 30 and 36, so as to prevent the turning of the member 39 in the di-' rection of the arrow in Fig. 1. This is supplemental to the clamping action of the nut 44. The long, gently curved edge 48, and the short, sharply curved edge 59 of the member 39 merge with and form a continuation of the curvature of the walls 30, 32, 34 and 36 to develop the contour best seen in Fig. 1, which, if followed by a cutting edge would give the propeller, at about the center portion thereof, the curvatures seen at 54 and 56 in Fig. 4.

l The operation is as follows:

The piece of wood or blank to be cut into a propeller is first shaped as shown in Fig. 3 to form the narrow portions 58, and the central hub portion Gil, and is provided with the hole 62, it being understood that the blank shown in Fig. 3 is otherwise rectangular in cross-section as seen in Figs. 5 to 8. yVhen the blank has been so shaped, it is placed in the dismantled jig, as shown in Fig. 2 with the'bolt 42 passing upwardly through the hole 62. The washer 64 is then passed over the bolt 42 to rest on top of the blank and the member 39 is placed on top of the washer t4 and clamped in position by the nut M. The process of assembling just described is clearly illustrated in Figs. 2 and 5, and when the jig with the blank in it has been completely assembled, it will appear as shown in Fig. 6. With the blank thus clamped in the jig, and the jig clamped to a work bench orv the like, the operator uses a knife or other cutting tool and proceeds to cut the upper part of the blank always guided by the varying contour presented by the upper edges of the walls 30, 32, 3d, 36, 48 and 59. By this means the operator will be forced to cut in a series of varying and intersecting planes passing through the opposite edges of the differently curved and slanted edges of the walls 36, 32, 34, 36, 48 and 59, thus generating a surface of a camber or pitch predeterminedby the progressively varying profile of the jig. The part thus removed is represented diagrammatically by the dotted lines in Fig. 13. The operator now removes the nut 44, top member 39 and washer 6 and, prior to reversing the blank for the cutting of the opposite face thereof, he inserts in the jig either the adjustable brace shown in Figs. 14 to 16, or the modified form of brace shown in Figs. 17 to 19.

The adjustable support shown in Fig. 16 consists of the bottom plate 66 and the upper plate 68 which are yieldably interconnected in toggle fashion by the links 79 and the spring 12 with the setscrew 'M to clamp the parts shown in any desired position. Either one such adjustable brace is used and is transferred from one end of the jig to the other as the cutting progresses, or two such adjustable braces can be used, one for each end of the jig to support both ends of he propeller simultaneously.

When one side of the blank has been out and the adjustable brace is positioned in the jig as shown in Fig. 14, the blank is turned up-sidedown so that the face thereof, which has been cut, is now resting on the adjustable brace and the operator now proceeds to cut the other side of the blank. When the second side of the blank has been cut, it will appear as shown diagrammatically in Fig. 15. The adjustable brace shown in Fig. 16 is made detachable and separate from the jig so that it may be positioned at any point along the jig thus serving to support a propeller as long as the jig, or one that is shorter than the jig, as the case may be. Instead of the adjustable, tensioned, brace shown in Fig. 16, I may use the modified form of brace best seen in Fig. 19 and which is in the nature of a bridge having .the opposite wedge-shaped members 16 and 18 which are interconnected by the cross bar 83, the wedge-shaped members l8 and i8 being so shaped as to fit in or cooperate with the predetermined contour of the walls of the jig. As shown by the sections II and [2, the blank, when out according to the contour predetermined by the jig, will have a predetermined pitch or camber. Inasmuch as the leading surface of the propeller has a different camber from that of its trailing edge, and in order to be able to carve both the trailing and leading edges by means of the same jig, I have provided the portion ofmy jig to the left of the center (as shown in Fig. 1) with a contour different from the contour of the portion of the jig to the right of said center, (as viewed in the same figure). When the blank is placed in the jig and the upper side of one end thereof has been cut on the left portion of the jig (as viewed in Fig. 1) the blank is removed and turned about its vertical axis to bring the other end thereof into the same left portion of the jig, to be carved along the same contour. When the one entire surface of the propeller has been cut, the blank is again removed from the jig, turned up-side-down, about its horizontal axis, and then the other face of one end of the propeller is cut in the portion of the jig to the right of center, and when this end has been cut, the blank is again removed and turned about its horizontal axis to bring the other end of the blank intothe right hand portion of the jig. In other words, one side of the propeller is cut throughout its length in the portion of the jig to the left of center, and the other side of the propeller, also throughout the length thereof, is cut in the portion of the J'ig to the right of center. After the opposite faces. of the blank have been carved to the proper pitch or camber as predetermined by the walls of the jig, the initially square ends of the blank are tapered off along the dotted lines 92 as shown in Fig. 4.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A propeller jig comprising an elongated channel adapted to support the blank to be cut, the central portion of said jig being formed to correspond to the shape of the central portion of a propeller and the longitudinal walls of said channel being of different heights, contours and proportions, whereby, a plane guided by the upper edges of said walls will generate a surface having a predetermined camber, a part of said central portion of the jig being formed detachable to permit insertion and removal of said blank.

2. A propeller jig comprising an elongated channel adapted to support the blank to be cut, the central portion of said jig being formed to correspondto the shape of the central portion of a propeller and the longitudinal Walls of said channel being of different heights, contours and proportions, whereby, a plane guided by the up- 

